1. Field of the Invention
The present invention generally relates to incrementers for use in digital applications and, more particularly, to very high speed incrementers having particular application in the central processor unit (CPU) of digital computers and especially microprocessors.
2. Background Description
There are many hardware and software related operations that require an incrementer to generate a digital value which is increased by one over a previous digital value. For example, in the process of accessing instructions in sequential order, an incrementer is required to generate instruction addresses. This function is often performed by a program counter; however, in the execution of a complex program, there are many branch instructions requiring a current instruction address to be temporarily stored. Then, when the program resumes at the stored instruction address, it is necessary to reload the program counter and advance the count. This function is often performed by an adder, but in either case, there can be a significant delay due to the ripple of the count through the counter or adder.
This is but one of many applications in digital computing and control technologies requiring an incrementer. While many digital circuits have been significantly improved in performance, not much attention has been given in the past to the function of the incrementer.